Small bowel atresia

Small bowel atresia (also known as small intestinal atresia) is a congenital condition in which a portion of the small intestine fails to develop properly, resulting in a complete obstruction (blockage) of the intestinal lumen. This condition encompasses duodenal atresia (ICD-10: Q41.0), jejunal atresia (Q41.1), and ileal atresia (Q41.2), depending on which segment of the small bowel is affected. The atresia is thought to result from a vascular accident during fetal development that disrupts blood supply to a segment of the developing intestine, leading to ischemic necrosis and resorption of the affected bowel. Duodenal atresia may also arise from failure of recanalization of the duodenal lumen during embryogenesis and is notably associated with Down syndrome (trisomy 21) in approximately 20-30% of cases. Small bowel atresia presents in the neonatal period, typically within the first day or two of life. Key symptoms include bilious (green) vomiting, abdominal distension, and failure to pass meconium (the first stool). Prenatal ultrasound may reveal polyhydramnios (excess amniotic fluid) and a dilated, fluid-filled bowel loop. In duodenal atresia, a characteristic 'double bubble' sign is seen on prenatal ultrasound or postnatal abdominal X-ray, representing the dilated stomach and proximal duodenum. The condition is classified into several types (Types I through IIIb and Type IV) based on the anatomical nature of the obstruction, ranging from an intraluminal membrane to complete separation of bowel ends with a mesenteric gap. Treatment is surgical and is required urgently after birth. The specific procedure depends on the location and type of atresia but generally involves resection of the atretic segment and primary anastomosis (reconnection) of the healthy bowel ends. For duodenal atresia, a duodenoduodenostomy is the standard repair. Outcomes have improved significantly with advances in neonatal surgery and intensive care, and survival rates now exceed 90% in most centers. However, complications such as short bowel syndrome (particularly with extensive or multiple atresias), intestinal dysmotility, and the need for prolonged parenteral nutrition may occur. Long-term prognosis depends on the length of remaining functional bowel and the presence of associated anomalies.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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